const resize = {
    // 指令的名称
    bind(el, binding) {
      // el为绑定的元素，binding为绑定给指令的对象
      let width = '';
      let height = '';
      function isReize() {
        if (document.defaultView) {
          const style = document.defaultView.getComputedStyle(el);
          if (width !== style.width || height !== style.height) {
            binding.value(); // 关键
          }
          width = style.width;
          height = style.height;
        }
      }
      el.__vueSetInterval__ = setInterval(isReize, 300);
    },
    unbind(el) {
      clearInterval(el.__vueSetInterval__);
    },
  };
  
  export default {
    install(app) {
      app.directive('resize', resize);
    },
  };
  